[AdrianEGraphene]

Yes, it's a bigger problem in these countries, [1] potentially because of the use of multi-country languages spoken by massive numbers of people.

Re: if really you'd want (and could have) something that does the job better.

I'd argue that nothing is better than blockchain in terms of dealing with monetary policy in each country. Since this solution is 100% targeted at the economic incentives that drive phone spam, the reward must be a financial incentive that is easy to globally implement and furthermore allow a user to easily transact with, regardless of country. P2P currencies means someone else in whatever country can worry about designing services that take/use Nano, while I focus on blocking phone spam and don't get wrapped up in potential race/optimization conditions in using "funny money". /rant

Doesn't mean this is a killer app, just as you said, 1 way of trying to solve this 30 year old problem that will only get worse over time as the Internet of Things matures.

[1] https://truecaller.blog/2019/12/03/truecaller-insights-top-2...